1. Field of the Invention
This invention relates to a method of preparing an antibiotic composition which imparts stability to the antibiotic when used in an animal feed. This invention provides a method of preparation of particles of an antibiotic which particles are stable to the environment surrounding the antibiotic when it is incorporated in the animal feed.
2. Description of the Prior Art
A number of antibiotic materials are used in the treatment of animals for the control of infectious diseases, for improving the rate of growth of the animals, or for improving the utilization by the animals of the feed they ingest. Among the antibiotics used for these various purposes, there can be named tylosin.
Tylosin is a well-known agricultural antibiotic drug. It was first disclosed in Hamill et al., U.S. Pat. No. 3,178,341 (Apr. 13, 1965), which patent taught the production of tylosin by fermentation with microorganisms identified as NRRL 2702 and NRRL 2703, which are obtainable from the Northern Utilization Research and Development Branch, U.S. Department of Agriculture, Peoria, Ill. Tylosin is well known to be effective against staphylococcus, mycobacterium, klebsiella, streptococcus and diplococcus organisms.
The antibiotic, although useful in the treatment of these various diseases, and capable of being administered orally in the feed of animals, unfortunately is inclined to instability brought about by the co-ingredients which contact the antibiotic in the final feed mixed for administration to the animals, and therefore suffers a considerable loss of potency.
The period of time over which it is important to maintain the antibiotic in its stabilized condition, after mixing with the animal feed and until the consumption by the animals of the feed, is relatively short, varying from a few days to a few months, i.e., perhaps three months. Since the concentration of antibiotic required in the feed ration is extremely low, it is customary to supply the antibiotic in the form of a relatively concentrated premix of the antibiotic in an edible carrier. This premix is then blended with the desired animal ration and the mixture is then fed to the animals in meal form or in pelleted form.
Thus, for example, to protect the tylosin from deterioration when the tylosin is incorporated as a feed premix into an animal feed, gelatin has for some time been used to coat the tylosin particles. However, the current cost of gelatin and the growing scarcity of gelatin prompted research to discover other means of stabilizing the tylosin for use in the feed premixes and in the animal feeds.
Since a high percentage of the cattle, swine and poultry feed sold and used in the U.S.A. is in the pelleted form, and the antibiotic is less stable in the pelleted form of feed, it is important to find a way to make the antibiotic more stable under these conditions of use.